The invention relates generally to touch panel display systems and more particularly, to sealing light beam touch panel systems against electromagnetic energy interference.
Patents disclosing such touch panel display systems include U.S. Pat. No. 3,764,813 to Clement et al. granted Oct. 9, 1973; U.S. Pat. No. 3,775,560 to Ebeling et al. granted Nov. 27, 1973; and U.S. Pat. No. 4,198,623 to Misek et al. granted Apr. 15, 1980. In systems such as these where light beam sources direct beams of light across the face of a display toward light beam detectors located on the other side of the display, electromagnetic energy may escape from the display unit and allow its detection and it may also interfere with sensitive electronic equipment in the immediate area. Also, external electromagnetic energy may enter the display unit and interfere with its operation. Prior electromagnetic energy shielding arrangements for touch panel display units have been complex, bulky, and have not been sufficiently integrated with the display unit. These prior arrangements have in some cases made maintenance of the display unit more difficult and have typically not been of the type which also enhance display operations.
Various internal touch panel circuits as well as various display circuits generate signals which may radiate from the display unit. Where square wave signals are used inside the display unit, harmonics of relatively high frequency may escape. Where the touch panel display unit is to be used in an environment requiring the control of compromising emanations, suppressing the radiation of such signals may be required in order to avoid detection. In the case where the display unit is located near other equipment which radiates electromagnetic energy, such as a radar system, exposure of the display unit circuits to that energy may cause faults, processing errors or have other detrimental effects on display unit operation. As used herein, electromagnetic energy interference refers to signals which are of lower frequency than that of the touch panel light beams.
Accordingly, it is an object of the invention to provide an improved, integrated electromagnetic energy interference sealing arrangement for a light beam touch panel display system.
It is also an object of the invention to provide an integrated, electromagnetic energy interference shielding touch panel system that provides shielding in combination with certain other features to result in a simpler, lower cost, operator adapted touch panel system for displays.
It is also an object of the invention to provide an integrated touch panel system which enhances display viewing, enhances operator/touch panel interaction, and facilitates maintenance.
It is also an object of the invention to provide a touch panel system which, along with electromagnetic energy shielding arrangements, is integrated into a front panel bezel which permits easier disassembly and maintenance.